<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .paopao {
            width: 400px;
            height: 150px;
            border-radius: 30px;
            margin: 40px auto;
            background: url(images/paopao.png) no-repeat left top , url(images/paopao.png) no-repeat right bottom;
            background-color: skyblue;
            transition:background-position .5s;
        }
        .paopao:hover {
            background-position: right bottom, left top;
        }
    </style>
</head>

<body>
    <div class="paopao"></div>
</body>

</html>